In the liquid argon calorimetry system of the ATLAS experiment at the CERN Large Hadron Collider in Geneva, Switzerland, nearly a quarter million signal and calibration lines are required to pass through the walls of the ATLAS calorimeter cryostats. Signal feedthroughs for such applications can be constructed using individual pins sealed in glass or ceramic, but the conductor density required for the ATLAS calorimeter greatly exceeds the densities typically achieved using pin-based feedthrough technology. The two feedthrough planes, one extremely cold, the other relatively warm, would have to be very large to accommodate the required number of lines, resulting in a bulky device. The bulky design would complicate the assembly of the device and the installation of the requisite plumbing services in its vicinity. In addition, the large number of connectors required along the readout path would add to the construction expense and also result in degradation in signal quality.
An alternative to sealed pin technology for the fabrication of cable feedthrough devices entails the use of epoxy materials for the formation of vacuum-tight seals, as described in W. D. Wood and W. L. Wood, "Hermetic Sealing with Epoxy" in Mechanical Engineering, March 1990, Pave Technology Co. This technology, however, is suitable only for devices exposed to temperatures down to about -65.degree. C.
Thus, there continues to be a need for a cable feedthrough device of compact design that is readily and inexpensively fabricated, and is also capable of maintaining vacuum-tightness even at very low temperatures. The device and process of the present invention meet this need.